Hurricane Sandy battering the U.S. East Coast on the morning of October 29.
NASA

Wireless companies up and down the East Coast have been preparing throughout the weekend to ensure that wireless service remains up and running for communities affected by Hurricane Sandy. But will it be enough?

Hurricane force winds, torrential rain, and tidal surges as a result of the storm are expected to wreak havoc along the coast on Monday and into Tuesday. Millions of people from Virginia to New England are expected to lose power. But the wireless phone companies are working to ensure their networks hold up during the storm.

Sandy has already caused some wind and flood damage in states such as North Carolina, Virginia, Maryland, Delaware, New York, and New Jersey. But so far, the cell phone networks have held up pretty well, with none of the major carriers reporting outages.

Wireless companies say they've been working around the clock to ensure their customers stay connected when they most need it.

Verizon said that it prepares for these types of disasters year round. And the company has emergency plans in place with technicians ready to respond.

"Verizon wireline and wireless business units have activated national and regional command and control centers, enabling Verizon operations teams to monitor the storm's progress and company operations, including network performance," the company said in a statement.

AT&T, which claims to have spent more than $600 million on emergency preparedness since 1991, said that it has an "arsenal of disaster response equipment and personnel" on standby.

Sprint Nextel says that it is also well-prepared. And one spokeswoman told me the company has been sandbagging network properties on flood-prone areas since Friday. The company has also been fully fueling permanent generators at its network properties which will give 48 to 72 hours of power at cell sites when local power goes out. And it has staged fully fueled portable generators if needed once the storm passes.

T-Mobile says that it also has backup generators at cell sites ready to go as well as microwave technology equipment that can be used if landline backhaul infrastructure is damaged at actual cell sites. The company also has cell-on wheels, or COWS as they are called, to roll into communities or areas where cell service is disrupted.

Wireless companies have been through similar natural disaster scenarios on several occasions. The most recent was Hurricane Irene, which swept over the East Coast a year ago. The preparations for Irene paid off. None of the carriers reported serious outages. But, of course, damage from Hurricane Irene was less than anticipated, with areas near the coast mostly being spared while regions inland were affected by excessive rain and flooding.

Hurricane Sandy is likely to turn out differently, as authorities report that tidal surges have already reached Irene levels in places like lower Manhattan in New York City. And the storm is still hours from making landfall.

Still, it's difficult to say right now if the cell phone networks will hold up under the extreme weather pressures. To better understand the risks, let's look at how these networks operate and where they are likely to be most vulnerable.

Keeping the cell tower power running. These cell towers require power to keep the radio transmitting signals. Without power, cell sites can no longer function. Carriers keep back-up generators and batteries at these cell towers to make sure they are still running when the commercial power is out. Sprint says it has enough power at its back-up sites to last for 48 to 72 hours. Once the storm passes and it's safe for crews to be out in the field, they can continue to refuel these generators and keep wireless service up and running, even when commercial power is still out for several additional days.

Wind and water damage to the cell sites. The equipment that transmits signals to cell phones sits high atop towers and other structures. The equipment used on these towers is environmentally hardened, but there are limits -- and there is potential for failure from both wind and water damage. If the wind and rain becomes so extreme to knock out transmission of a tower, wireless providers have temporary and portable towers ready to be deployed to fill in until repairs can be made. These cell-on wheels, or COWS, can be rolled into communities or areas where cell service is disrupted.

Damage to the "backhaul" lines and other communications infrastructure. Wireless networks are only wireless from your cell phone to the wireless tower transmitting the signals. Then the voice call or data session is routed over fiber-optic cables that are usually underground. Much like road system, connections feed into each other until they reach the bigger "highways," which have multiple lanes or capacity for transporting cargo. If one of the landline cables serving as a major "highway" or connection for an area is severed or damage, it's likely to cause disruption to hundreds if not thousands of wireless customers. Luckily, communications networks are built with redundancy in mind, so if one part of the highway is blocked, traffic will travel on a different link.

A Verizon representative told me the company has made sure that its splice cases, which hold the cables carrying communications, are sealed and that the air pressurization systems are working to protect this infrastructure. Even under normal and sunny conditions, some of these cable are underwater in manholes, and they operate just fine.

Overloaded and congested networks may make calls temporarily difficult to make. Wireless networks are built so that a tower provides signal to a cell or a small region. There is only so much capacity that a single cell site can handle. And if every customer in that cell site is making a phone call at the same time, the network can become overloaded. What this means for people trying to make phone calls is that the calls will be dropped or won't go through. Data networks won't connect or they will upload or download information very slowly. If the network is really congested, the connection will be dropped.

This is why it's very hard to make a phone call when you're at a place with a large number of people, such as at a football stadium.

The best way to communicate if the network is overloaded is to send text messages. A voice call is connected or not, depending on how much capacity is available on the network. But if the network is congested, it will continue to try to send a text message over and over until it has been sent.

There is a chance that the network may become overloaded in an emergency situation. But because a hurricane unfolds over hours and days, it's less likely that people will make phone calls all at the same time. The volume of the calls made over a short period of time is what makes the network so congested that it's unusable. This is what happened during the earthquake on the East Coast last year. Some service disruptions occurred for a short of period of time following the earthquake, because so many people were trying to access the network at the same time.

The best thing wireless users can do as they prepare for the storm is to make sure their devices are fully charged and they have back-up batteries that are also fully charged. If you have a car, you should also have a car-charger for your phone so that you can recharge your battery if you lose power for several days. You are much more likely to lose commercial power than you are to lose complete service of your cell phone.

About the author

Marguerite Reardon has been a CNET News reporter since 2004, covering cell phone services, broadband, citywide Wi-Fi, the Net neutrality debate, as well as the ongoing consolidation of the phone companies. E-mail Maggie.
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